docs: def addSource(self, sourceUri, weight):
          """
          add a news source to the topic page
          @param sourceUri: uri of the news source to add to the topic page
          @param weight: importance of the news source (typically in range 1 - 50)
          """
          assert isinstance(weight, (float, int)), "weight value has to be a positive or negative integer"
          self.topicPage["sources"].append({"uri": sourceUri, "wgt": weight})